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Tesla Tales

Carlos R. Villa National High Magnetic Field Laboratory. Tesla Tales. NHMFL Overview. One Of Three National Labs In The Southeast U.S. One Of A Dozen High Magnetic Field Labs In The World Only One In Western Hemisphere Largest And Highest Powered In The World. NHMFL Overview.

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Tesla Tales

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  1. Carlos R. Villa National High Magnetic Field Laboratory Tesla Tales

  2. NHMFL Overview • One Of Three National Labs In The Southeast U.S. • One Of A Dozen High Magnetic Field Labs In The World • Only One In Western Hemisphere • Largest And Highest Powered In The World

  3. NHMFL Overview • User Laboratory • Close to 1100 User Visits in 2010 • NSF & State of Florida Funded • Research Free To Scientist • Research In Many Fields (Not Just Magnets!!) • Materials Science, Physics, Engineering, Chemistry, Biology, Biomedical, Geochemistry, Microscopy…

  4. Center for Integrating Research & Learning • Educational component of NHMFL’s grant • K-12 education outreach • 10,961 students visited this school year • Professional development • Workshops and conferences facebook.com/MaglabEducation

  5. Special Opportunity - RET 2013 • RET program • 6 weeks in the summer • $3600 stipend

  6. Magnet Review • Gauss • Measurement Of Magnetic Field • Named For Carl Friedrich Gauss • Tesla • Measurement Of Larger Magnetic Fields • Named For Nikola Tesla • 10,000 Gauss = 1 Tesla

  7. Tesla Tales • Magnetism • Ferromagnetic, paramagnetic, diamagnetic • 1820 Revolution • Oersted & Ampere • Faraday’s laws of induction • Lenz’s Law • Free electron theory of conduction • BCS theory of superconductivity

  8. Magnetism • Motion of electrons create magnetic fields • In some atoms, spins cancel out • Pauli exclusion • Whenever all electrons spin the same direction: magnetic field is produced • Magnetic domains • In magnets: lined up

  9. Ferromagnetism: Permanent Magnets • Electrons tend to line up in groups (Domains) • Domains reinforce other domains • Turn material magnetic • Examples: Refrigerator Magnets, Bar Magnets, Magnetite, Horseshoe Magnets, Hematite, etc… • Field can be lost • Curie Point • Electric Current • Degaussing • Bang It

  10. Ferromagnetism: Temporary Magnets • Domains temporarily aligned • Will keep magnetic field until tampered • Examples: • Paperclips, scissors, staples, thumb tacks, pins, screwdrivers, refrigerator door, car doors, etc… • Anything that is magnetic, but will not keep its field

  11. Paramagnetism: Temporary Magnets • No force aligning domains • Randomly distributed • Domains temporarily aligned by strong field • Will lose magnetic field when original field is removed • Examples: Aluminum can, copper wire, gold jewelry, tungsten, etc…

  12. Diamagnetism: Counter Aligned Magnets • Domains temporarily aligned by strong field • Will align in order to oppose original field • Faraday’s second law of induction • When a material whose atoms do not normally have a magnetic field is placed in a strong field, their electrons will adjust in such a way as to create their own magnetic field opposing the external one. • WATER!

  13. Ferromagnetism Lab: Magnetic Fields • Magnets attract and repel • Seeing fields • Bar magnet • As many compasses as possible

  14. Ferromagnetism Lab: Temporary Magnets • Paper clips • Argument driven inquiry • How long will temporary magnets hold? • 36 months! • Do they have poles? • They attract and repel! • Can they be unmagnetized? • Yes, but they can also hold fields!

  15. Ferromagnetism Lab: Compass Creation • Magnetize An Item • Allow It To Float • Must Turn Freely • Needle • Petri Dish • Coffee Stirrer • Water • Permanent Magnet

  16. Diamagnetism Lab • Superconductors are diamagnetic • YBCO or BSSCO works well • Kit available from Colorado Superconductor Inc.

  17. 1820: Oersted Discovery • An electrical current can create a magnetic field • Oersted set up lecture demonstration • Used battery to supply current • Showed compass needle deflecting near the wire

  18. Oersted Lab • Deflect a compass needle • Battery • Aluminum foil • Compass • Wire • Assorted other items • Place the compass: • Above the wire • Below the wire

  19. 1820: Ampere’s Law • Moving electrical charges produce magnetic fields • Simple experiment • Two straight wires • Current passed through • Wires bowed toward or away • Led to electromagnets

  20. Ampere Lab • Materials • Copper wire • Iron rod (or nail) • Battery • Extensions: • 2 batteries • In line? • Aluminum, wooden rod • Will they work?

  21. Ampere Lab: Part II • Right hand rule • Direction of field (Biot-Savart Law) • Poles (Winding direction) • Use compass • Variables: • Neatness • Number of winds • Wire gauge • Battery strength

  22. 1831: Faraday’s Laws • A change in magnetic field produces an electric current • Induction • Magnetic flux: The change needed to induce current

  23. Faraday Lab • Use copper wire to attach LED lights on a plastic pipe. • Drop NIB magnet through pipe (and through copper wires) • Induction of electricity

  24. 1835: Lenz’s Law • An induced current in a wire (by flux) will flow to create a field that opposes the flux • Eddy currents created • Used in magnetic braking systems • Rollercoasters • Electric car braking feedback

  25. Lenz Lab • Changing Magnetic Flux Produces An Induced Electric Field • Copper Tube, NIB Magnet • Eddy Currents

  26. 1900: Free Electron Theory • Electrical conduction in a solid is caused by the bulk motion of electrons • Each metal atom contributes an electron that is free to roam • Voltage briefly accelerates the electrons • Resistance is friction • Each electron is everywhere • Like a wave in a pool

  27. Free Electron Theory Lab • Current electricity • Electrons flow through a wire • Slow movement • Circuit needed • Complete circuits using Alien Ball • Turn on the light bulb • Turn on two light bulbs • Create more advanced circuits • Parallel & series

  28. 1957: BCS Theory • BCS: Bardeen, Cooper, Schreiffer • At low temperatures, some metals lose resistance • Atoms nearly stationary • Superconductivity results from the formation of Cooper pairs • Two electrons partnered • One follows the other • Results in frictionlessflow of electrons

  29. BCS Lab • Repeat Ampere lab • Measure resistance with digital multimeter at each step • Raise temperature with hot water • Lower temperature with ice water • Lower temperature with liquid nitrogen* • Always adhere to safety guidelines • Goggles, Cryogenic gloves, and covered footwear

  30. Additional Resources Stop Faking It: Electricity & Magnetism Bill Robertson Driving Force: The Natural Magic of Magnets James D. Livingston

  31. Additional Resources A Short History of Nearly Everything Bill Bryson The Nature of Science James Trefil

  32. Additional Resources Hidden Attraction: The Mystery & History of Magnetism Gerrit L. Verschuur The Cold Wars: A History of Superconductivity Jean Matricon & Georges Waysand

  33. Additional Resources • http://education.magnet.fsu.edu • MagLabAlpha; Science, Optics, & You; other curriculum • MagLab audio slideshows • RET Program • K-12 Programs

  34. Carlos R. Villa National High Magnetic Field Laboratory villa@magnet.fsu.edu • 850-644-7191 Thank You

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